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Biomedical subjects

J B Whitfield

Publications and source records attributed to J B Whitfield.

At least 55 records · Page 3Linked to original sources
PubMed1992

Effects of increasing the rate of alcohol metabolism on plasma acetate concentration.

Plasma acetate concentration is increased during alcohol metabolism. However, measures which increase the rate of alcohol metabolism do not always increase plasma acetate concentration. Plasma samples from normal male subjects who had been given alcohol and then either fructose or glucose were analysed for acetate. Although each of these carbohydrates increased the mean rate of alcohol metabolism, only fructose increased the plasma acetate concentration. It was concluded that the further metabolism of acetate produced from alcohol may be increased by glucose.

Acetates↗
PubMed1991

Biological markers of alcoholism.

Biological markers are biochemical or physiological characteristics which may help to classify a person according to the presence or absence of some disease or risk of disease, either with respect to their current status or future susceptibility. Many biological markers related to alcoholism have been described; this review suggests a classification of them and indicates areas where they are well-established and other areas where further investigation may be useful.

Journal Article↗
PubMed1991

Protease inhibitor frequencies: is there a deficit of M subtype heterozygotes?

A large number of reports on human protease inhibitor (PI) type frequencies in various populations have now appeared. A combination of the results of published studies shows that the observed frequencies of the M subtype homozygotes and heterozygotes differ significantly from those predicted by the Hardy-Weinberg equilibrium, especially among Europeans but probably not among Asians or Africans. The M1, M2 and M3 homozygotes are more numerous than would be expected, while the M1M2 and M1M3 heterozygotes are less common than expected.

Africa↗
PubMed1991

The effect of fructose on alcohol metabolism and on the [lactate]/[pyruvate] ratio in man.

Ten male subjects were given alcohol by intravenous infusion and maintained at a constant blood alcohol level. The rate of alcohol metabolism was measured before and after an oral dose of fructose (100 g), as the amount of alcohol required to maintain the steady state. The mean rate of alcohol metabolism increased by 80% after fructose but there was considerable variation among the subjects, which was related to their plasma fructose concentrations. Blood lactate increased after fructose to a greater degree than blood pyruvate, resulting in a significant increase in [lactate]/[pyruvate] ratio. Since fructose increased the [lactate]/[pyruvate] ratio when it increased alcohol metabolism, the action of fructose cannot be explained by a decrease in the liver cytoplasmic [NADH]/[NAD] ratio and some other mechanism must be sought.

Adolescent↗
PubMed1991

Effect of humidification on the airways of cats during high-frequency ventilation.

The effect of humidity on the histologic lesions induced by high-frequency jet ventilation was investigated in 12 healthy cats. After 16 hours of ventilation, the appearance of the tracheal epithelium ranged from normal to necrotic. The damage was considerably more severe in the trachea of cats of the group ventilated without added humidity. Increasing the relative humidity to 63% at 24 C had a protective effect, but further increasing the relative humidity to 92% at 35 C did not appear to provide significantly more protection. The bronchi and distal airways had minimal, if any, damage in all groups.

Animals↗
PubMed1990

Parasitoids, polydnaviruses and endosymbiosis.

Symbiotic associations traditionally have been treated as evolutionary curios rather than as a major source of evolutionary innovation. Recent research on a wide variety of organisms is changing this view and is breaking down the barriers between the traditional categories of parasitism, commensalism and mutualism, to produce a more flexible view of multispecific interactions. An especially abundant, but little discussed, mutualism exists between parasitoid wasps in the superfamily Ichneumonoidea and a novel form of DNA viruses known as polydnaviruses. Mutualisms between viruses and eukaryotes are not often reported, although as many as 100 000 species of organisms may exhibit this unusual association. In this review Jim Whitfield considers what is known about the parasitoid-polydnavirus relationship and how (and from what) it might have arisen.

Journal Article↗
PubMed1990

Alpha-1-antitrypsin (protease inhibitor) phenotypes and longevity.

We have tested the hypothesis that the protease inhibitor phenotypes MZ and MS are disadvantageous and reduce survival by comparing the prevalence of these phenotypes in a group of 707 very old people (hospital patients) with the prevalences reported in younger populations of blood donors. The MS and MZ phenotypes appear to be no less common among those who have survived to old age, but a highly significant difference was found in the occurrence of the M subtypes. The M1 type was more common in the elderly, and the M heterozygotes were less common than would be predicted from the reported incidence in younger groups and from the Hardy-Weinberg equilibrium. This discrepancy appeared to be smaller in subjects of Mediterranean origin than in those of British or Irish genetic background.

Aged↗
PubMed1989

Effect of diet on [lactate]/[pyruvate] ratios during alcohol metabolism in man.

Ten subjects received alcohol by intravenous infusion on two occasions, after five-day periods on high- or low-carbohydrate diets. Blood [lactate]/[pyruvate] ratios were significantly higher during fasting alcohol metabolism after the low-carbohydrate, high-fat diet. The carbohydrate/fat balance in the diet may affect cytoplasmic-mitochondrial NADH transfer. Dietary composition may modify the metabolic changes caused by alcohol.

Adult↗
PubMed1988

Surgical management of bilateral diaphragmatic paralysis in a dog.

Bilateral diaphragmatic paralysis of uncertain cause developed in a 3-month-old Golden Retriever. A surgical procedure for tightening the diaphragmatic muscle was used to help alleviate the dog's respiratory distress. During thoracotomy, the central tendon of the diaphragm was plicated, using an interlocking suture pattern. The dog improved after surgery, and although complete recovery from paralysis was achieved only on one side, the dog has remained clinically normal 1 year after surgery.

Animals↗
PubMed1988

Effect of oral glucose on the rate of metabolism of ethanol in humans.

We have tested whether the effect of carbohydrate on the rate of alcohol metabolism can be reproduced by glucose alone. Ten male subjects were given ethanol by intravenous infusion until a steady state was established and 100 g glucose in solution was then taken orally. The rate of alcohol metabolism, measured as the rate of infusion required to maintain a constant breath alcohol reading, increased significantly after glucose but there were differences between the subjects. The presence or absence of a change in the rate of alcohol metabolism after glucose was associated with the subject's fasting rate and with their glucose tolerance.

Administration, Oral↗
PubMed1987

Differing effects of carbohydrate, fat and protein on the rate of ethanol metabolism.

The rate of metabolism of ethanol in humans has been assessed by intravenous infusion of ethanol/saline under feedback control to maintain a constant blood alcohol concentration. After equilibration, meals consisting predominantly of carbohydrate, fat or protein were eaten and changes in ethanol metabolic rate were found. Carbohydrate caused a significant increase in this rate and fat or protein caused small but non-significant decreases. Infusion of ethanol/saline resulted in a temporary fall in plasma free fatty acid levels and a steady rise in plasma triglycerides. The changes in alcohol metabolism following carbohydrate cannot be accounted for by changes in insulin, free fatty acid or lactate/pyruvate levels.

Adult↗
PubMed1986

Genetic variation and plasma creatine kinase activity.

The distribution of plasma creatine kinase (CK; E.C.2.7.3.2) is known to be skewed, and this has made it difficult to analyse the sources of variation. We have studied plasma CK in 206 pairs of twins and have analysed the results after separating them into what appear to be two Gaussian frequency distributions. The results in the main distribution (CK less than 300 iu/1) are apparently affected by genetic factors common to both men and women, and by environmental factors which are of much greater effect in men. The tendency for some men to have very high CK values may also have a genetic basis.

Adult↗
PubMed1986

High-frequency jet ventilation during pneumothorax in dogs.

Pneumothorax (45 ml of N/kg of body weight insufflated into the pleural space) in anesthetized dogs ventilated with air caused a significant (P less than 0.05) increase in pleural pressure, central venous pressure, capillary wedge pressure, and venous admixture. Cardiac index (CI) and arterial O2 tensions were decreased. Ventilation with 100% O2 increased arterial O2 tensions, but did not affect calculated intrapulmonary shunting of blood or CI. Application of 10 cm of H2O-positive end-expiratory pressure in the presence of pneumothorax during positive-pressure ventilation and high-frequency jet ventilation reduced intrapulmonary shunting of blood, which remained higher than control values, and caused a further decrease in CI. Cardiopulmonary function during pneumothorax in anesthetized dogs was more profoundly affected by the application of positive end-expiratory pressure than by the form of mechanical ventilation.

Animals↗
PubMed1986

Are specimens with "at risk" biochemical profiles more likely to be infectious for hepatitis B virus?

The potential infectivity of 640 plasma specimens with various biochemical profiles was directly assessed by hepatitis B virus (HBV) DNA dot-hybridization. We found that specimens with "at risk" biochemical profiles typical of various forms of liver disease were not significantly more likely to carry HBV than the general patient population. Specimens containing HBV cannot be distinguished from non-infectious specimens by any simple biochemical tests, including aminotransferases and bilirubin. The only predictive feature of HBV-positive samples was that they were more likely to be labeled as "biohazardous" by the medical staff, but even this was not always the case.

DNA, Viral↗
PubMed1985

High-frequency jet ventilation during bronchoscopy in a dog.

A dog with severe pulmonary disease caused by Filaroides osleri (Oslerus osleri) infection was anesthetized with thiopental sodium IV for diagnostic bronchoscopy. The dog was ventilated continuously during bronchoscopy with a high-frequency jet ventilator (using a rate of 100 breaths/min, drive pressure of 20 psi, and inspiratory fraction of 0.30). High-frequency jet ventilation provided satisfactory ventilatory support during bronchoscopy despite the dog's pulmonary disease.

Animals↗
PubMed1985

Genetic and environmental causes of variation in renal tubular handling of sodium and potassium: a twin study.

We have conducted a study of renal sodium and potassium reabsorption in 205 pairs of twins on freely chosen diets; 89 of the subjects were studied on more than one occasion. Renal tubular sodium and potassium handling, as measured by the fractional excretions FENa and FEK, show repeatable differences between individuals. Siblings (in this case monozygotic and dizygotic pairs of twins) are more alike in this respect than unrelated individuals. Comparison of monozygotic and dizygotic twin pairs indicates that genetic, rather than shared environmental, factors are probably responsible for this similarity, with heritability estimates of 0.5 for sodium and 0.6 for potassium. There are indications of sex differences in the sizes of the genetic and environmental effects for both variables and indications that the genetic effects may be qualitatively different for FEK. Such findings need further investigation.

Adolescent↗
PubMed1985

Genetic and environmental influences on the size and number of cells in the blood.

The heritabilities of human blood cell characteristics were estimated in a study of 206 pairs of young adult twins, male and female. White cell numbers, indices related to circulating red cell mass (haemoglobin, red cell count, and haematocrit), and platelet numbers and size all appeared to be accounted for by genetic and nonshared environmental influences only. Mean cell volume (of the erythrocytes) appeared to be influenced by environmental factors shared by siblings as well as the other two sources of variation. Correlation between red cell count and haemoglobin is modulated by both genetic and environmental factors, but the negative correlation between red cell numbers and size is due mainly to genetic factors independent of those influencing haemoglobin. A significant negative correlation also exists between platelet numbers and size. In males, alcohol consumption increased mean cell volume, and genetic factors influencing alcohol consumption are partly responsible for the correlation between them.

Adolescent↗